1. Field of the Invention
The present invention relates to novel peptides having a nootropic effect and being useful as medicines, particularly as antidementia agents.
2. Description of Prior Art
Vasopressin has been previously known as a compound having a nootropic effect, i.e., intelligence developing effect. Recently, it has been reported that peptides seemingly corresponding to a vasopressin fragment, for example, those having the following formulae: ##STR4## have such a nootropic effect as that of vasopressin in Science, 221, pp.1310-1312 (1983) and Brain Research, 371, 17(1986).
Further, there is also reported that a peptide having the following formula: ##STR5## has a nootropic effect in Japanese Patent Provisional Publication No.59(1984) 93036.